Non-dispersive infrared (NDIR) gas detectors are known for sensing the presence and concentration of various gases. Many known NDIR-type detectors are more in the nature of laboratory instruments than relatively small, rugged and convenient sensors for use in the field. As a result, many of the known detectors have suffered from complexity and relatively high cost.
Airborne contaminants such as particulate matter or water vapor can adversely affect detector outputs. Filtering is known to exclude particular matter. Filtering, however, may not exclude water vapor. Other known NDIR-type detectors have attempted to address environmental conditions, such as condensation of water vapor in the gas being sampled by heating the sample chamber electrically. Such heaters and their power supplies result in added bulk, weight and cost in the respective detectors.
There thus continues to be a need for NDIR-type detectors which do not require either electrical heating, or large amounts of space, electromechanical choppers and the like, or, complex processing circuitry. Preferably, such chambers could be inexpensive to manufacture, and require little or no adjustment or field maintenance.